SUZANNE BIEHN STEWART, MDDIVISION OF UROLOGY

DUKE UNIVERSITY MEDICAL CENTER

Urolithiasis: Etiology, Symptoms, and Management

Overview

Urinary stones have plagued humans since the beginning of recorded history

Initial stones uncovered in mummified remains of Egyptians ~7,000 years ago

Overtime, we have made drastic improvements in our understanding of stone formation and

treatment strategies

Babayan RK et al. “Urinary Calculi and Endourology,” Handbook of Urology, 3rd ed. 2004

Learning Goals

1. Risk factors for stone disease2. Economic implications3. Various types of stones4. Causes of stone development5. Common symptomatology6. Acute Evaluation tools7. Differentiate patients that need immediate vs

delayed intervention8. Various options for treatment9. Treatment complications10. Recommended follow-up

Epidemiology—1

Overall 1-3% of adults are affected in industrialized nations

In the US, highest prevalence is in the Southeast (the Stone Belt)

Courtesy of Preminger GM.

Epidemiology—2

Natural History and Risk Factors

Peak incidence age: 30-60 years

Race: 4-5x more common in whites than blacks

Family history: 3 fold risk

Body size: risk with weight

Epidemiology—3

Changing TrendsHistorically….

Stones were 3x more common in males than females

Currently…. Males are only 1.3x more likely to form stones than

females (2002) Secondary to changes in diet, lifestyle and increased obesity

in females

Scales et al. 2005

Epidemiology—4

Changing Trends in Hospital Discharges for Renal Calculus by Gender

21.0%, p = 0.001

12.2%, p = .002

Scales et al. 2005

Epidemiology—5

Stones are Common…Annual incidence in males = 1%Lifetime risk in white males = 20%Life long disease

Risk of recurrence after first stone: Year 1 10 - 15% Year 5 50 - 60% Year 10 70 – 80%

Average of 9 yrs intervening between episodesAnd Costly…

In US, stone disease accounts for > 400,000 hospitalizations annually

Epidemiology—6

Economic ImplicationsIn 1993, inpatient and outpatient costs

estimated$2.39 Billion/year1

By 2050, its estimated that there will be 1.6-2.2 million extra stone cases in the US secondary to global warming Leading to an additional healthcare cost of 0.9—1.3

billion/year2

1Thompson et al. 1995; 2Pearle M. 2o08

Etiology—1

Stone development is complex and multifactorial Causes are specific to the type of stone formed (ie stone

composition) > 90% of patients a metabolic etiology can be found

General pathophysiology principals:1. Supersaturation: Urine becomes oversaturated with a type

of solute, which then comes out of solution (crystallization) Dehydration, urinary obstruction and stasis

2. Inhibitor deficiency: Urine normally has substances which block crystallization (ie citrate and magnesium)

Dietary deficiencies

Etiology—2

Influential Factors in Stone Formation1. Dehydration

Major player in majority of stones Geographic location: high temperatures

2. Anatomic obstruction and urinary stasis3. Metabolic/Urine composition

Urinary pH Increased stone forming substances (calcium, oxalate, uric acide) Decreased stone inhibiting substances (citrate and magnesium)

4. Diet5. Urinary tract infection

Urease producing organisms: Proteus, Klebsiella, Pseudomonas, Serratia

Etiology—2

Influential Factors in Stone Formation6. Sedentary lifestyle/immobilization

Increased bone reabsorption increases urinary calcium7. Disease states

1. Sarcoidosis2. Hyperparathyrodism3. Inflammatory bowel disease4. Chronic diarrhea5. s/p Gastric bypass6. Cystinuria7. Gout

8. Medications1. HIV Protease inhibitors: Indinavir and Nelfinavir

Etiology—2

Types of Stones1. Calcium-based: ~80% all stones

a. Calcium oxalate1. Most common stone formed in industralized nations2. Most common type of bladder stone3. Radio-opaque4. Very difficult to dissolve5. Dehydration = common influential factor

Calcium oxalate

Dihydrate crystals

Monohydrate crystals

Etiology—3

Types of Stones

1. Calcium-based:b. Calcium phosphate

1. ~10% of calcium stones

2. Influential factors: Hyperparathyroidism, UTI, dehydration

2. Non-calcium-baseda. Uric Acid (8%)

1. In pure form radiolucent2. Form in acidic urine (pH < 6.0)3. Dissolves with alkalization of urine

Calcium phosphate crystals

Etiology—4

Types of Stones2. Non-calcium-based

a. Uric Acid (8%)4. Dehydration = common influential factor5. Patients usually have normal plasma and urine

uric acid levels

Uric acid stone

Uric acid crystals

Etiology—5

Types of Stones2. Non-calcium-based

b. Struvite (10%)1. Often called “infectious stones”2. Associated with UTI3. Majority of staghorn calculi are struvite composition4. Form in alkaline urine5. Radio-opaque

Struvite stone

Struvite crystal

Etiology—6

Types of Stones2. Non-calcium-based

c. Cystine (1%)1. Caused by cystinuria—homozygous recessive disorder2. Forms in acidic urine3. Dissolves with urinary alkalization4. Radio-opaque5. Resistant to Extracorporeal Shock Wave Lithotripsy (ESWL)6. May form staghorns

Cystine stone Cystine crystal

Etiology—7

Anatomic Locations for Stone Formation

Can form and be found anywhere along the urinary tract

1. Kidneya) Stone nidus typically starts to develop

2. Uretera) Stone nidus can form here secondary:

1. Obstruction—i.e. stricture2. Foreign object—i.e. stent

3. Bladdera) Stone nidus can form here secondary:

1. Dysfunctional bladder2. Obstruction—i.e. BPH3. Foreign object

Symptoms—1

Not all patients with stones have symptoms

Stones become symptomatic when:1. Cause obstruction and irritation

Typical sites of obstruction: Ureteral Pelvic Junction (UPJ) Ureter crosses over Internal iliac

vessels Ureteral Vesical Junction (UVJ)

2. Associated with infection

Symptoms—2

Classic symptoms: Obstruction Acute, colicky pain

Can be severe May have associated nausea and vomiting Location of pain can suggest location of stone

Flank Abdominal Radiate to groin or testicle

Irritation urothelial lining Hematuria Gross or microscopic

Irritation of bladder lining Lower urinary tract symptoms Frequency Urgency Dysuria

If associated with infection Fever

Evaluation—1

Laboratory tests: CBC—elevated white blood cell count BMP—elevated creatinine UA—positive nitrites, leukocyte esterase

Order Urine culture If febrile—Blood cultures

Imaging: Non-contrasted CT

1st line diagnostic test Locate stone Determine stone size Identify signs of obstruction

• hydronephrosis and hydroureter KUB, Intravenous pyelogram (IVP), US

Evaluation—2

Success of spontaneous stone passage is correlated with: Location of stone:

Distal > Proximal

Stone size: 95% of stones < 5 mm will pass

within 40 days

Stone width (mm)

Approx % stones passed1

Mean time to

passage2

1 90%8 days

2 85%3 83% 11 days4 77%

22 days5 56%6 41%7 30%

?8 21%9 3%

1Urology 10(6); 1977. Am J Roentgenol 178:101;2002. 2J Urol 162:688; 1999

Evaluation—3

Which patients should undergo….Trial of Passage (Surveillance) vs. Surgical

InterventionIndications for Hospital Admission:

1. Fever2. Signs of infection

a) Elevated WBC3. Solitary kidney4. Intractable pain5. Unable to tolerate fluid secondary to nausea/vomitting6. Renal deterioration

a) Elevated creatinine attributed to obstruction

Treatment—1

Trial of Passage (Surveillance)Patient candidates:

Afebrile, pain controlled, no overt signs of infection or renal compromise

Medical management: Oral hydration Analegesics: tylenol, narcotics Alpha blockers: Tamulosin (Flomax)

Relaxes ureteral smooth muscle Increases stone passage rates up to ~ 44% Decreases time to stone passage by ~2-4 days Decreases pain associated with stone passage

Re-evaluate with imaging ~4-6 weeks If stone remains….INTERVENTION becomes necessary

Treatment—2

Patients with Active Infection

Initial treatment: Antibiotics Drainage of kidney

Ureteral stent Percutaneous nephrostomy tube

Proceed with stone removal after infection has cleared

Double J ureteral stents

Nephrostomy tube

Treatment—3

Treatment strategy based on….Stone Size and Location

Options: Kidney and ureteral stones:1. Extracorporeal Shock Wave Lithotripsy (ESWL)2. Percutaneous nephrolithotomy with lithotripsy (PCNL)3. Ureteroscopy with lithotripsy/extraction4. Open surgery (rare) Bladder stones:1. Cystolitholapaxy2. Cystolithotomy (open surgery)

Treatment—4

ESWLMost common 1st line treatment for renal calculi

Indications: Non-obstructed renal or ureteral calculi < 1.5-2 cm

Contraindications: Pregnancy Coagulopathy AAA (> 4cm) Cystine, infectious stones (relative contraindication)

Advantages: Non-invasive Sedation only required Outpatient intervention

Disadvantages: Patients MUST pass stone fragments

Complications: Steinstrasse 4-9%—may require 2nd intervention Hematoma—renal/retroperitoneal

Treatment—5

PCNLIndications:

Renal pelvis calculi ~ > 2cm Staghorn calculi Proximal ureteral calculi ~ > 1cm UPJ obstruction

Contraindications: Coagulopathy

Advantages: High stone free rate

Renal stones—95% Ureteral stones—75%

Disadvantages: Anesthesia Overnight hospital stay Ureteral stent and/or nephrostomy tube in perioperative period

Treatment—6

Complications with PCNL1. Bleeding

Risk of transfusion = 3% Hemodynamically unstable

Return to the OR Hemodynamically stable

Large diameter nephrostomy tube and clamp tube to tampanode bleeding Nephrostomy tampanode balloon catheter Angiography and embolization

2. Pneumothorax/Hydrothorax Percutaneous access:

Above 12th rib—10% risk of fluid in pleura Above 11th rib—10% risk of pneumothorax/hydrothorax

Signs/symptoms: Pleuritic chest/flank pain, loss of breath sounds, respiratory distress/desaturation

Treatment—6

Complications with PCNL3. Bowel Injury

~0.2% risk Colonic injury more common

Left access Morbidly obese

Intraoperative detection: contrast in colon with nephrostogram Postoperative signs: Fecaluria, pneumaturia,peritoneal signs, fever,

ileus, leukocystosis4. Renal pelvis laceration/perforation

Can occur with dilation of percutaneous tract Commonly detected intraoperatively Postoperatively: common symptom—flank pain

Treatment: Placement of large bore nephrostomy tube until tract closes

Treatment—7

Ureteroscopy (URS)

Indications: Ureteral and lower pole renal stones Morbid obesity Bleeding diathesis Ectopic or horseshoe kidney

Tools (aka toys): Semi-rigid vs. flexible ureteroscope Lithotripsy: laser, pneumatic, electrohydralic, ultrasonic Extraction: stone grasper, basket

Advantages: Outpatient procedure High success rate of removal ~95% with Laser lithotripsy of ureteral stones

Disadvantages: Anesthesia Possible need for ureteral stent placement

Treatment—8

Complications of URS

1. Ureteral false passage 0.4-0.9% Entrance into ureteral orifice Passing guidewire around impacted stone Tx: Stent

2. Ureteral perforation 1-15% More common with semi-rigid URS Tx: Stent

3. Avulsion ~0.3% Basketing large stone in proximal or mid-ureter Complete avulsion requires operative repair

4. Ureteral Strictures 0-4% Late complication Increased risk with impacted stone, perforations

Extravasation of contrast indicating perforation

Ureteral orifice

Follow Up Care—1

Abbreviated Metabolic evaluation First episode, solitary stone, uncomplicated

course UA, Ucx, stone analysis, BMP, Ca2+,

Phosphorus, uric acid Radiographic imaging

Extensive Metabolic evaluation Recurrent episodes, medical conditions alter

metabolism, non-calcium based stones Same as abbreviated evaluation plus

24 hr urine collection (~2x): urinary pH, volume, sodium, potassium, citrate, uric acid, magnesium, oxalate, chloride, protein, creatinine, cystine

Follow Up Care—2

General Dietary Recommendations

1. Oral fluid intake Keep urine volume 2-3L/day

2. Low sodium diet3. Low animal protein diet4. Low oxalate diet

Chocolate, tea, spinach, rhubarb, nuts, beets5. Moderate calcium intake

800-1000 mg/day

Specific recommendations based on metabolic evaluation

Clinical Scenario—1

64 yo female with no previous medical history presents to the ED with left lower quadrant

abdominal pain and fever. On CT, she is found to have diverticulitis and incidentally a 5mm, nonobstructing renal pelvic stone. How

do you manage the stone?a) PCNLb) ESWLc) URSd) No immediate intervention

necessary

Clinical Scenario—2

32 yo male with no past medical history presents to clinic with left abdominal pain, hematuria, temperature of 38.5C, WBC 16. On CT he has a left 7mm mid-ureteral stone.

What is the appropriate management?a) Immediate URSb) Trial of passage with flomax, narcoticsc) Schedule outpatient ESWLd) Hospital admission, abx, stent

Clinical Scenario—3

44 yo female POD #1 left PCNL with no nephrostomy tube develops worsening left flank pain, shortness of breath and shows a declining trend her oxygen

saturations. What is the next step?

a) Pain meds, nasal cannula, incentive spirometryb) Notify MD, likely needs

CXR—pnuemothorax/hydrothoraxc) Notify MD, likely needs CT scan—unidentified

renal pelvic perforationd) Notify MD, likely needs nephrostomy tube—

obstructing stone